prepare gtest runtime

Based on !168 (merged). Prepares deployment of ĞTest network with chainspecs made of custom genesis and easily customizable client specs (bootnodes...).

Build with

cargo build --features gtest --no-default-features

Run with

# reads genesis from file given in environment variable or generate one if not given
DUNITER_GTEST_GENESIS=./node/specs/gtest_genesis.json ./target/debug/duniter --tmp --alice --chain=gtest_de
# reads genesis and client spec from ./node/specs/gtest_*.json at runtime
./target/debug/duniter --tmp --alice --chain=gtest_live
# hardcoded genesis and client spec from ./node/specs/gtest_*.json at compile time
./target/debug/duniter --tmp --alice --chain=gtest

docs/dev/launch-a-live-network.md

@@ -67,7 +67,7 @@ An example of genesis configuration file: `resources/gdev.json`. Paste your sess
 ### Generate raw spec
 
 ```docker
-docker run -v $HOME/dev/duniter-v2s/resources:/var/lib/duniter/resources -e DUNITER_GENESIS_CONFIG=/var/lib/duniter/resources/gdev.json --rm duniter/duniter-v2s:TAG -- build-spec -lerror --chain=gdev-gl --raw > name-raw.json
+docker run -v $HOME/dev/duniter-v2s/resources:/var/lib/duniter/resources -e DUNITER_GENESIS_CONFIG=/var/lib/duniter/resources/gdev.json --rm duniter/duniter-v2s:TAG -- build-spec -lerror --chain=gdev_live --raw > name-raw.json
 ```
 
 ```bash